This application claims the benefits of Japanese Application Nos. 2000-143646, 2000-255886, 2000-266950, 2000-307709 and 2001-085183 which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates generally to an impact absorbing type steering column apparatus, and more particularly to a technology capable of making a collapse load variable.
2. Related Background Art
If an automobile collides with other automobile or a structure etc, a driver might suffer a secondary collision with a steering wheel by its inertia. The automobiles manufactured over the recent years broadly take an impact absorbing type steering shaft and an impact absorbing type steering column apparatus for the purpose of preventing the driver from being injured in that case. The impact absorbing type steering column apparatus is structured such that the steering column gets separated with the steering shaft when the driver suffers the secondary collision, and normally gets collapsed simultaneously with the steering shaft, and a collision energy is absorbed on that occasion.
What has hitherto been known as an collision energy absorbing system is a mesh system for causing a compression buckling deformation of a mesh member formed in a part of the steering column. As disclosed in Japanese Patent Application Post-Exam Publication No. 46-35527, however, there has been widely adopted a ball system in which metal balls are interposed between an outer column and an inner column and act to form plastic grooves in an inner peripheral surface of the outer column and in an outer peripheral surface of the inner column when collapsed.
Further, a drawing type system disclosed in Japanese Patent Application Laid-Open No. 7-329796 has also been taken over the recent years. A drawing type collision energy absorbing mechanism takes such a configuration that one side end of an energy absorbing member composed of, e.g., a band-like steel plate is fixed to a car body sided bracket, and a drawing member such as a steel rod etc fitted in a buckling portion formed in the energy absorbing member is provided on the side of the steering column and causes a drawing deformation of the energy absorbing member when the steering column shifts forward.
Moreover, a tear-up system disclosed in Japanese Utility Model Publication No. 5-68776 has partly been adopted. The tear-up type collision energy absorbing mechanism takes such a configuration that a central portion of the energy absorbing member composed of, e.g., a band-like steel plate is fixed to the car body sided bracket, two side portions of the energy absorbing member are fixed to the steering column in a way that bends it in a U-shape, and the energy absorbing member is torn up while being deformed by bending when the steering column shifts forward.
By the way, in each of the impact absorbing type steering column apparatuses described above, the steering column becomes collapsed when a predetermined collapse load acts, however, this collapse load is normally set based on a kinetic energy generated when a driver having a standard weight secondarily collides with the steering wheel. If the driver is a small-sized women and when a car speed is low, however, as a matter of course, the kinetic energy thereof decreases, and the energy absorption quantity can not be adjusted corresponding to a driver""s physique, a car speed etc.
It is a primary object of the present invention, which was devised to under such circumstances, to provide an impact absorbing type steering column apparatus capable of making a collapse load variable and adjusting an energy absorption quantity upon a secondary collision corresponding to a driver""s physique, a car speed etc.
To accomplish the above object, according to a first aspect of the present invention, an impact absorbing type steering column apparatus provided with collision energy absorbing mechanism for absorbing an energy of a secondary collision of an occupant upon a collision of a vehicle, comprises an energy absorption quantity adjusting member for changing a secondary collision energy absorption quantity of the collision energy absorbing mechanism, at least one sensor for detecting a condition of the occupant or the vehicle, and an electric control unit for controlling a drive of the energy absorption quantity adjusting member on the basis of a result of detection by the sensor.
According to the first aspect of the invention, for example, if a weight of the driver is heavy and when a car speed is high the control unit controls a drive of the energy absorption quantity adjusting member, thereby increasing the collapse load with which the collision energy absorbing mechanism operates. While on the other hand, if the weight of the driver is light and when the car speed is low, the control unit decreases the collapse load with which the collision energy absorbing mechanism operates. The collapsible column thus properly gets collapsed.
According to a second aspect of the present invention, the impact absorbing type steering column apparatus according to the first aspect of the invention may comprise a collapsible column rotatably supporting a steering shaft and getting collapsed with a predetermined collapse load, wherein the collapsible column includes an outer column, an inner column entering the outer column when the collapsible column gets collapsed, and the collision energy absorbing mechanism has a plurality of metal balls interposed between the outer column and the inner column and forming plastic grooves in at least one of the outer column and the inner column when the collapsible column gets collapsed.
According to the second aspect of the invention, for instance, the electric control unit, if the weight of the driver is heavy, increases the collapse load by setting larger the number of plastic grooves formed by the metal balls. By contrast, the electric control unit, if the weight of the driver is light, decreases the collapse load by setting smaller the number of plastic grooves. The collapsible column thus properly gets collapsed.
According to a third aspect of the present invention, in the impact absorbing type steering column apparatus according to the second aspect of the invention, the plurality of metal balls may be constructed of a first group of metal balls retained in first metal ball retaining means and a second group of metal balls retaining in second metal ball retaining means, and the energy absorption quantity adjusting member may be provided with a retaining member rotational driving mechanism for rotating at least one of the first group of metal balls and the second group of metal balls in order to make a part or the whole of angular phases of the metal balls in the first metal ball group with respect to the collapsible column coincident with or different from the metal balls in the second metal ball group.
According to the third aspect of the invention, for example, the electric control unit having detected the weight of the driver etc outputs a drive command to the retaining member rotational driving mechanism in order to rotate the first metal ball retaining member or the second metal ball retaining member.
According to a fourth aspect of the present invention, the impact absorbing type steering column apparatus according to the first aspect of the invention may further comprise a steering column for rotatably supporting the steering shaft, and a car body sided bracket, fixed to the car body, for supporting the steering column and allowing the steering column to get released therefrom when an impact load equal to or larger than a predetermined value acts, wherein the collision energy absorbing mechanism may be provided between the steering column and the car body sided bracket, and a drawing member may cause a plastic deformation of an energy absorbing member composed of a metal plate or a metal wire with a shift of the steering column.
According to the fourth aspect of the invention, for instance, the electric control unit, if the weight of the driver is heavy, increases the operation load by augmenting the plastic deformation quantity of the energy absorbing member. By contrast, the electric control unit, if the weight of the driver is light, decreases the operation load by reducing the plastic deformation quantity of the energy absorbing member.
According to a fifth aspect of the present invention, in the impact absorbing type steering column apparatus according to the fourth aspect of the invention, the drawing means may be a metal rod or a metal ball, and the energy absorption quantity adjusting mechanism may change at least one of a plastically deformed portion and a plastic deformation quantity of the energy absorbing member by the drawing member.
According to the fifth aspect of the invention, for example, the drawing member for the energy absorbing member involves the use of four lengths of steel rods. The electric control unit, if the weight of the driver is heavy, operates all the four steel rods and, if the weight of the driver is light, moves the two lengths of steel rods to a retreat position or increases and decreases a drawing depth with respect to the energy absorbing member by use of the two steel rods.
According to a sixth aspect of the present invention, the impact absorbing type steering column apparatus according to the first aspect of the invention may further comprise a steering column for rotatably supporting the steering shaft, and a car body sided bracket, fixed to the car body, for supporting the steering column and allowing the steering column to get released therefrom when an impact load equal to or larger than a predetermined value acts, wherein the collision energy absorbing mechanism may be provided between the steering column and the car body sided bracket, and may cause a fracture, or a bending deformation and the fracture of the energy absorbing member composed of the metal plate with a shift of the steering column.
According to the sixth aspect of the invention, for instance, a central portion of the energy absorbing member is fixed to the car body sided bracket, and two side portions thereof are connected to the steering column. The electric control unit, if the weight of the driver is heavy, gets the energy absorbing member torn up at two portions, thereby increasing the operation load. Further, the electric control unit, if the weight of the driver is light, disconnects one side portion of the energy absorbing member from the steering column and gets the energy absorbing member torn up at only one portion, thereby decreasing the operation load.
According to a seventh aspect of the present invention, an impact absorbing type steering column apparatus comprises a collapsible column rotatably supporting a steering shaft and getting collapsed with a predetermined collapse load. The collapsible column includes an outer column, an inner column entering the outer column when the collapsible column gets collapsed, and a plurality of metal balls interposed between the outer column and the inner column and forming plastic grooves in at least one of the outer column and the inner column in order to absorb a collision energy when the collapsible column gets collapsed. The steering column apparatus is provided with an energy absorption quantity adjusting member for changing an absorption quantity of the collision energy.
According to the seventh aspect of the invention, for instance, if the weight of the driver is heavy, the driver manually manipulates a changeover switch etc, thereby increasing the collapse load by setting larger the number of plastic grooves formed by the metal balls. By contrast, if the weight of the driver is light, the collapse load is decreased by setting smaller the number of plastic grooves. The collapsible column thus properly gets collapsed.
According to an eighth aspect of the present invention, in the impact absorbing type steering column apparatus according to the seventh aspect of the invention, the plurality of metal balls may be constructed of a first group of metal balls retained in first metal ball retaining means and a second group of metal balls retaining in second metal ball retaining means, and the energy absorption quantity adjusting member may be provided with a retaining member rotational driving mechanism for rotating at least one of the first group of metal balls and the second group of metal balls in order to make a part or the whole of angular phases of the metal balls in the first metal ball group with respect to the collapsible column coincident with or different from the metal balls in the second metal ball group.
According to the eighth aspect of the invention, for example, the driver manually manipulates the changeover switch etc, thereby outputting the drive command to the retaining member driving mechanism in order to rotate the first metal ball retaining member or the second metal ball retaining member.
According to a ninth aspect of the present invention, an impact absorbing type steering column apparatus comprises a steering column for rotatably supporting the steering shaft, a car body sided bracket, fixed to the car body, for supporting the steering column and allowing the steering column to get released therefrom when an impact load equal to or larger than a predetermined value acts, and a collision energy absorbing mechanism provided between the steering column and the car body sided bracket, for absorbing an energy of a secondary collision of an occupant by causing a plastic deformation of an energy absorbing member composed of a metal plate or a metal wire by use of a drawing member with a shift of the steering column, wherein the steering column apparatus is provided with an energy absorption quantity adjusting mechanism for changing an absorption quantity of the collision energy.
According to the ninth aspect of the invention, for instance, if the weight of the driver is heavy, the driver manually manipulates the changeover switch etc, thereby increasing the operation load by augmenting the plastic deformation quantity of the energy absorbing member. By contrast, if the weight of the driver is light, the operation load is decreased by reducing the plastic deformation quantity of the energy absorbing member.
According to a tenth aspect of the present invention, in the impact absorbing type steering column apparatus according to the ninth aspect of the invention, the drawing member may be a metal rod or a metal ball, and the energy absorption quantity adjusting mechanism may change at least one of a plastically deformed portion and a plastic deformation quantity of the energy absorbing member by the drawing member.
According to the tenth aspect of the invention, for example, the drawing member for the energy absorbing member involves the use of four lengths of steel rods. If the weight of the driver is heavy, the driver manipulates the changeover switch etc, thereby operating the all the four steel rods. By contrast, if the weight of the driver is light, the driver moves two lengths of steel rods to a retreat position or increases and decreases a drawing depth with respect to the energy absorbing member by use of the two steel rods.
According to an eleventh aspect of the present invention, an impact absorbing type steering column apparatus comprises a steering column for rotatably supporting the steering shaft, a car body sided bracket, fixed to the car body, for supporting the steering column and allowing the steering column to get released therefrom when an impact load equal to or larger than a predetermined value acts, and a collision energy absorbing mechanism provided between the steering column and the car body sided bracket, for absorbing an energy of a secondary collision of an occupant by causing a fracture, or a bending deformation and the fracture of the energy absorbing member composed of the metal plate with a shift of the steering column, wherein the steering column apparatus is provided with an energy absorption quantity adjusting mechanism for changing an absorption quantity of the collision energy.
According to the eleventh aspect of the invention, for instance, a central portion of the energy absorbing member is fixed to the car body sided bracket, and two side portions thereof are connected to the steering column. If the weight of the driver is heavy, the driver manually manipulates a changeover switch etc to get the energy absorbing member torn up at two portions, thereby increasing the operation load. Further, if the weight of the driver is light, the electric control unit disconnects one side portion of the energy absorbing member from the steering column and gets the energy absorbing member torn up at only one portion, thereby decreasing the operation load.
According to a twelfth aspect of the present invention, in the impact absorbing type steering column apparatus according to any one of the first through eleventh aspects of the invention, an electromagnetic actuator may be a driving source of the energy absorption quantity adjusting means.
According to the twelfth aspect of the invention, for example, the electric control unit, based on input signals from a variety of sensors, controls a drive of the electric actuator of the energy absorption quantity adjusting mechanism, thereby shifting a relative position of the drawing member with respect to the energy absorbing member.
According to a thirteenth aspect of the present invention, in the impact absorbing type steering column apparatus according to any one of the first through eleventh aspect of the invention, an electric motor may be a driving source of the energy absorption quantity adjusting mechanism.
According to the thirteenth aspect of the invention, for example, the electric control unit, based on the input signals from the variety of sensors, controls a drive of the electric motor of the energy absorption quantity adjusting mechanism, thereby shifting the relative position of the drawing member with respect to the energy absorbing member.
According to a fourteenth aspect of the present invention, in the impact absorbing type steering column apparatus according to any one of the first through eleventh aspects of the invention, the energy absorption quantity adjusting mechanism may change an absorption quantity of the secondary collision energy by the energy absorbing mechanism at leastwise three or more stages.
According to the fourteenth aspect of the invention, for instance, the electric motor moves forward or backward the slide block facing to the drawing pin with the aid of the screw mechanism, and a position of the drawing pin with respect to the energy absorbing member is shifted by a plurality of stepped portions formed on the slide block.
According to a fifteenth aspect of the present invention, in the impact absorbing type steering column apparatus according to any one of the first, fourth, fifth, ninth and tenth aspects of the invention, the energy absorption quantity adjusting mechanism may change an absorption quantity of the secondary collision energy by the energy absorbing means in an infinitely variable manner.
According to the fifteenth aspect of the invention, the electric motor moves forward or backward the slide block facing to the drawing pin with the aid of the screw mechanism, and a position of the drawing pin with respect to the energy absorbing member is shifted by an inclined surface formed on the slide block.
According to a sixteenth aspect of the present invention, in the impact absorbing type steering column apparatus according to any one of the first through eleventh aspects of the invention, the energy absorption quantity adjusting mechanism may change an absorption quantity of the secondary collision energy by the energy absorbing mechanism in two or more modes, and energy absorption loads may be substantially fixed with respect to a progress of a collapse stroke after points of inflections of energy absorption characteristics in the two or more modes.
According to the sixteenth aspect of the invention, in the case of a structure with a sufficient allowance of the collapse stroke, the energy absorption quantities suited respectively to the large- and small-sized physiques are obtained.
According to a seventeenth aspect of the present invention, in the impact absorbing type steering column apparatus according to any one of the first through eleventh aspect of the inventions, the energy absorption quantity adjusting mechanism may change an absorption quantity of the secondary collision energy by the energy absorbing mechanism in two or more modes, and energy absorption loads may gradually increase with respect to a progress of a collapse stroke after points of inflections of energy absorption characteristics in the two or more modes.
According to the seventeenth aspect of the invention, for instance, in the case of a structure with no sufficient allowance of the collapse stroke, if bottomed at a full stroke, a peak load occurs. A bottomed peak can be, however, eliminated by gradually increasing the load at the second half of the stroke.
According to an eighteenth aspect of the present invention, an impact absorbing type steering column apparatus comprises a collapsible column rotatably supporting a steering shaft and getting collapsed with a predetermined collapse load. The collapsible column includes an outer column, an inner column entering the outer column when the collapsible column gets collapsed, and a plurality of metal balls interposed between the outer column and the inner column and forming plastic grooves in at least one of the outer column and the inner column in order to absorb a collision energy when the collapsible column gets collapsed. The steering column apparatus is provided with a plurality of metal ball retainers for retaining the metal balls in phases different from each other, and a retainer separating mechanism for separating at least one of the metal ball retainers from the car body sided member in order to reduce the number of plastic grooves formed by the metal balls when the collapsible column gets collapsed.
According to an eighteenth aspect of the invention, for example, if the weight of the driver is heavy, all the metal balls are made to form the plastic grooves, thereby attaining a comparatively large collapse load. In contrast with this, if the weight of the driver is light, the retainer separating mechanism separates a part of the metal ball retainers from the car body sided member, thereby reducing the number of the plastic grooves. The collapsible column is thus collapsed with a comparatively small collapse load.
According to a nineteenth aspect of the present invention, in the impact absorbing type steering column apparatus according to the eighteenth aspect of the invention, the retainer separating mechanism may be an electrically driven actuator.
According to the nineteenth aspect of the invention, for instance, the electrically driven actuator is operated by an electric current given from a drive control unit integrally incorporated into the apparatus, and the collapse load is adjusted corresponding to the weight of the driver, a driving condition etc.
According to a twentieth aspect of the present invention, in the impact absorbing type steering column apparatus according to the nineteenth aspect of the invention, the electrically driven actuator may separate the metal ball retainer from the car body sided member only when being charged with electricity.
According to the twentieth aspect of the invention, even when a supply of the electric current to the electrically driven actuator is cut off due to an impact when collided and so on, the metal ball retainer is not separated from the car body sided member, and an unintended decrease in the collapse load is prevented.
According to a twenty first aspect of the present invention, an impact absorbing type steering column apparatus comprises a collision energy absorbing mechanism for absorbing an energy of a secondary collision energy of an occupant upon a collision of a vehicle, and an energy absorption quantity adjusting mechanism for changing an absorption quantity with which the collision energy absorbing mechanism absorbs the secondary collision energy, wherein an electromagnetic actuator is a driving source of the energy absorption quantity adjusting means, and a plunger of the electromagnetic actuator is adsorptively held in a predetermined position by a permanent magnet.
According to the twenty first aspect of the invention, for instance, when a first coil in the electromagnetic actuator is charged with the electricity, the plunger magnetically attracted by the first coil is moved to a first position and adsorptively held by a first permanent magnet. Further, when the electrification is switched over to a second coil from the first coil, the plunger magnetically attracted by the second coil is moved to a second position from the first position and adsorptively held by a second permanent magnet.
According to a twenty second aspect of the present invention, in the impact absorbing type steering column apparatus according to the twenty first aspect of the invention, the collision energy absorbing mechanism may be provided between the steering column and the car body sided bracket and may cause a plastic deformation of an energy absorbing member composed of a metal plate or a metal wire by use of drawing means with a shift of the steering column.
According to the twenty second aspect of the invention, for example, if the weight of the driver is heavy, the operation load is increased by augmenting the plastic deformation quantity of the energy absorbing member. By contrast, if the weight of the driver is light, the operation load is decreased by reducing the plastic deformation quantity of the energy absorbing member. The steering column thus properly moves forward.
According to a twenty third aspect of the present invention, in the impact absorbing type steering column apparatus according to the twenty first or second aspect of the invention, the drawing means may be a metal rod or a metal ball, and the energy absorption quantity adjusting mechanism may change at least one of a plastically deformed portion and a plastic deformation quantity of the energy absorbing member by the drawing member.
According to the twenty third aspect of the invention, for example, the drawing member for the energy absorbing member involves the use of four lengths of steel rods. If the weight of the driver is heavy, all the four steel rods are used and, if the weight of the driver is light, the two lengths of steel rods are moved to a retreat position, or there is increased or decreased a drawing depth with respect to the energy absorbing member by use of the two steel rods.